A magnetic deflection up-date: field equations, CRT geometry, the distortions and their corrections

The evolution of the magnetic deflection yoke to wide angles and high performance, and the modification of cathode-ray-tube (CRT) structures has responded to ever-more-demanding performance in diverse applications. This article probes the past to extract those basics by which precise deflection performance of CRT systems may be calculated. Development of beam-patch plots from a yoke's magnetic-field plot leads to a simplified equivalent constant-strength field. The characteristics of yoke behavior are established. An ideal yoke configuration, which does not distort the electron beam's focused spot, is identified. Its angular deflection is proportional to field strength; response is linear. A unified treatment of diverse CRT geometries provides precise deflection equations. Geometric distortion components are identified, their equations developed, and correction methods described.